• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1525-1527
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• 2008

기존 케이블 puller 방식의 EPB 시스템은 제동력을 측정하기 위하여 hall effect force 센서를 이용하고 있다. 그러나 본 논문에서는 hall effect force 센서를 사용하는 대신 모터의 속도를 이용하여 제동력이 가해지는 시점을 결정한 이후 모터의 회전수에 따른 제동력 추정 기법을 제안하고 실험을 통하여 검증한다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1528-1530
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• 2008

기존의 EPB 시스템에서는 제동력을 측정하기 위하여 hall effect force 센서를 이용하고 있지만, 이 센서는 비싼 가격과, 구조상 장착의 어려움 등의 문제점을 가지고 있다. 본 논문에서는 hall effect force 센서에 비해 저가이며, 기구적인 면에서 단순한 구조를 가지는 전류 센서만을 이용하여, 모터 유도 전류와 각가속도 정보를 획득하고, 이것을 이용하여 EPB 제동력을 추정하는 기법을 제안하고 실험을 통해 검증한다.

• Journal of the Korean Society for Railway
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• v.9 no.6 s.37
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• pp.682-688
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• 2006

In this paper, a method which can deduce the traction farce or the braking force from the acceleration or the deceleration of the train, has been suggested. In the case of Korean high speed train (HSR-350x), the traction force and the braking forces have been obtained by using this method. It is proven that the proposed method is a very good tool in estimating the traction force or the braking force when the train starts or stops. Also, these forces on be used to calculate friction coefficients of mechanical brakes and the transmission efficiency of the traction system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.3 s.246
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• pp.295-301
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• 2006

The wheel slip control systems are able to control the braking force more accurately and can be adapted to different vehicles more easily than conventional ABS systems. In order to achieve the superior braking performance through the wheel-slip control, real-time information such as the tire braking force at each wheel is required. In addition, the optimal target slip values need to be determined depending on the braking objectives such as minimum braking distance, stability enhancement, etc. In this paper, a robust wheel slip controller is developed based on the adaptive sliding mode control method and an optimal target slip assignment algorithm. An adaptive law is formulated to estimate the longitudinal braking force in real-time. The wheel slip controller is designed using the Lyapunov stability theory and considering the error bounds in estimating the braking force and the brake disk-pad friction coefficient. The target slip assignment algorithm is developed for the maximum braking force and searches the optimal target slip value based on the estimated braking force. The performance of the proposed wheel-slip control system is verified In simulations and demonstrates the effectiveness of the wheel slip control in various road conditions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.5
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• pp.517-523
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• 2004

Recently, wheel slip controllers with controlling the wheel slip directly has been studied using the brake-by-wire actuator. The wheel slip controller is able to control the braking force more accurately and can be adapted to various different vehicles more easily than the conventional ABS systems. The wheel slip controller requires the information about the tire braking force and road condition in order to achieve the control performance. In this paper, the tire braking forces are estimated considering the variation of the friction between brake pad and disk due to aging of the brake, moisture on the contact area or heating. In addition, the road friction coefficient is estimated without using tire models. The estimated performance of tire braking forces and the road friction coefficient is evaluated in simulations.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.4
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• pp.8-17
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• 2010

In this paper, a fault tolerant control against sensor faults of electric parking brake (EPB) is proposed. Fault tolerant control method of EPB system is strongly demanded since sensor faults can endanger a driver's safety. In this paper, a clamp force estimation method is presented using motor's armature current and angular velocity. Clamp force estimation method is applied for fault detection method with parity equations. The goal of the detection method is to detect and identify faults in encoder, current sensor, force sensor, and parking cable. And a switching logic for fault tolerant control against the three sensor faults is suggested. Experimental results show that the proposed force estimation method satisfies the specifications of EPB system. The effectiveness of the fault detection method is validated with experimental results. Although a single sensor fault happens, EPB system with the proposed fault detection method does not develop into a failure on subsystem or system level.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.12
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• pp.2291-2299
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• 2008

Hall effect force sensors have been used to measure clamping force in conventional Electric Parking Brake(EPB) systems. Estimation of clamping force without the sensors has drawn attentions due to mounting space limitations and cost issues. Removing the sensor requires the estimation of the initial contact point where the clamping force is effectively applied to the brake pads. In this paper, we propose how to estimate the initial contact point finding the relation between the angular velocity of an actuator and the initial contact point. For force estimation a look-up table is used as a function of the displacement of parking cable from the initial contact point. The proposed method is validated by experiments. From the experimental results we observe that the proposed method satisfies the specifications. The designed method is also able to estimate clamping force although parking cables are loosened and brake pads are worn out. Applying the proposed method enables manufacturing of low cost EPB systems.